/**
 * Copyright 2011-2019 Asakusa Framework Team.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.asakusafw.dag.runtime.adapter;

/**
 * A buffer for building keys.
 * @since 0.4.0
 */
public interface KeyBuffer {

    /**
     * Returns a view of this buffer.
     * @return a view
     */
    View getView();

    /**
     * Returns a frozen view of this object.
     * @return a frozen view
     */
    View getFrozen();

    /**
     * Resets the buffer contents.
     * @return this
     */
    KeyBuffer clear();

    /**
     * Appends a value into this buffer.
     * @param value the target object
     * @return this
     */
    KeyBuffer append(Object value);

    /**
     * Represents a key for {@link DataTable}.
     */
    public interface View {
        // no special members
    }
}